2020년 Vol.37 No.02
Background & Objective : Recommended dosage of apixaban for non-valvular atrial fibrillation is 5 mg b.i.d.. Reduced dosage 2.5 mg b.i.d. is recommended for patients meeting the dose reduction criteria. In clinical practice, low dosage of apixaban is frequently administered in patients not meeting the reduction criteria. We compared the efficacy and safety of apixaban between the dosage of 5 mg b.i.d. and 2.5 mg b.i.d. in patients recommended with 5 mg b.i.d..
Methods : This study included patients younger than age 80 not meeting the dosage reduction criteria. Patients were classified into Group A who took apixaban 5 mg b.i.d. and Group B who took 2.5 mg b.i.d.. The efficacy endpoint was the incidence of ischemic stroke and systemic embolism. The safety endpoint was the incidence of major and non-major bleeding events.
Results : Among the eligible 127 patients, 57 patients were in Group A and 70 were in Group B. The mean age of patients was older in Group B (age 68.1 vs 72.8 yrs, p<0.001). The estimated glomerular filtration rate was lower in Group B (65.2 mL/min) than Group A (74.1 mL/min) (p=0.016). Group B had more heart failure and hypertension and less thromboembolic history than Group A (p<0.05). Ischemic stroke and systemic embolism occurred in four cases (7%) in Group A and four cases (5.7%) in Group B (p>0.999). No major bleeding events occurred in both groups, and non-major bleeding occurred seven cases (12.3%) and eight cases (11.4%) (p=0.882).
Conclusion : Dosage of 2.5 mg b.i.d. lower than recommended was preferentially used in older patients, with lower renal function, heart failure, and hypertension or without thromboembolic history. Low dosage apixaban showed no difference in drug efficacy and safety. Through further studies, it is worth considering newer guidelines to review specific conditions such as renal function, underlying diseases, and thromboembolic history among the elderly.